If you're a playwright or director who loves some wonderful work of art or literature and can't wait to turn it into a play, just pause a moment.

If you’re a playwright or director who loves some wonderful work of art or literature and can’t wait to turn it into a play, just pause a moment. Look at the things you think are theatrical, then steal them; no one is watching. Tell everyone you thought of them yourself, make your own play, and if you get caught, call it an homage. If you don’t follow this process, you might end up with a play like “The Conversation,” which has a few nifty moments but ends up vanishing in the long shadow of its source material.

Francis Ford Coppola’s marvelous 1974 film “The Conversation,” which the new stage adaptation follows slavishly, is a showcase for Gene Hackman’s performance as Harry Caul. Here, David Mogentale plays the role — a wiretapper in possession of a harmless-sounding recording that may not be everything it seems to be.

Caul has risen to the top of his profession by walking the razor’s edge between knowing too much and knowing too little, always getting the recordings he’s required to make but never listening to them too carefully. He does this because he once learned the fate of a few of his subjects, and he’s spending the rest of his life trying to forget it.

Eventually, however, Caul’s need for human contact overcomes his carefully tended caution and paranoia, pushing him into the spotlight at exactly the wrong time.

Mogentale emits a certain magnetism as the troubled loner, which goes a long way toward making the antisocial character palatable. Equally competent is Julianne Carpenter, who plays a variety of roles, including Caul’s evanescent love interest, Meredith.

Both actors have battles to fight before they can ever get to the text, though. Painfully miscast, Carpenter tries to re-create Meredith as the same kind of husky-voiced sexpot (as played by Elizabeth MacRae in the movie) to whom Hackman opened up. This isn’t something she can or should do, but it seems in keeping with director Leo Farley’s vision for the play, which also requires Mogentale to spend a lot of time wandering twitchily around the set — like Hackman in the film.

Coppola pulled off a neat trick in 1974: He convinced his audience that his movie was as closed-in as Caul, bound by the warehouse walls and tortured by the weird noises made by Caul’s reel-to-reel tape players. In reality, the film is pretty expansive, using the great outdoors as the counterpoint to Caul’s claustrophobic life — which is hard to achieve in a small studio theater.

Ultimately, the most basic element that eludes the stage version is a pretty simple one: repetition. For us to really understand what’s going on inside Caul’s brain, we have to pick apart the conversation from every different angle. Coppola shot it once and went back to it again and again; Farley has his actors perform it over and over, and that makes it different every time.

The play’s denouement finally helps us understand why writer Kate Harris and Farley took on the project, but by then we don’t care. Next time Harris and Farley see a great movie, here’s hoping they take the good stuff and rework it into something new.

The Conversation

29th Street Rep; 80 seats; $20 top

Production

A 29th Street Rep presentation of a play in two acts by Kate Harris, adapted from the film by Francis Ford Coppola. Directed by Leo Farley.